X-ray target changer using a translating anode

ABSTRACT

Means for moving in two orthogonal directions the target anode of an X-ray tube within the tube body comprising bellows inserted between the tube body section and a glass-insulator section, the anode being fixed to the sealing flange of the insulator section. Longitudinal translation means are attached to the flange by which the insulator section is mounted to the bellows. Operation of the translation means moves the anode and insulator section relative to the tube since the bellows can contract or expand.

[ 51 June 5,1973

United States Patent Carter TRANSLATING ANODE Primary Examiner-Roy Lake Assistant Examiner-Darwin R. Hostetter l gg ai t f g gg g 8 st St Attorney-R S. Sciasc1a, Arthur L. Brannmg and .Phihp Schneider Nov. 24, 1971 [54] X-RAY TARGET CHANGER USING A [76] Inventor:

[22] Filed:

57 ABSTRACT Means for moving in two orthogonal directions the target anode of an X-ray tube within the tube bod 21 Appl. No.: 201,698

3 comprising bellows inserted between the tube body section and a glass-insulator section, the anode being 740 526 NM 13 32 113 00 MR3 3 mm 3 "u mm WWS l r d saw UIF' 1]] 2 00 555 [ll fixed to the sealing flange of the insulator sectio Longitudinal translation means are attached to the [56] References Cited UNITED STATES PATENTS flange by which the insulator section is mounted to the bellows. Operation of the translation means moves the anode and insulator section relative to the tube since the bellows can contract or expand.

2,209,963 8/1940 Du Mond 3,331,978 7/1967 Brown et al.

5 Claims, 3 Drawing Figures PATENTEDJUN 51913 SHEET 1 BF 2 INVENTOR FORREST CARTER FIG. I.

PATENTED 3.737, 698

SHEET 2 [IF 2 WATER FLOW ENToR FORREST L. CARTER X-RAY TARGET CHANGER USING A TRANSLATING ANODE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates to X-ray tubes and especially to anode translation means for such tubes.

The most common type of X-ray tube is the sealed typed. This type is limited to harder radiations, such as CuK and MoK, because the thickness of the vacuumtight X-ray window (usually Be foil) causes it to absorb too much of radiations softer than CrK. For these sealed tubes, a change of targets requires: (1) shutting off the power and discharging the high-voltage circuitry; (2) turning off the water supply and draining the cooling coils and the X-ray tube on the tube stand; (3) disconnecting the high-voltage cable and demounting the X-ray tube; and (4) reversing this procedure in mounting an X-ray tube of a different target.

In the production of soft X-ray radiation, unsealed tubes are employed. These use such a thin window that the pressure differential across the window must be limited to a few torr or the window will be ruptured. Also, in this case, the X-ray tube body is usually left in place and only the anode containing the target material is replaced. To the procedure for changing an X-ray tube described above must be added a step involving the release of the vacuum on both sides of the window so that the window material will not be ruptured. Similarly, after the anode is replaced, a vacuum must be drawn in such a way that the window is not ruptured.

Soft X-rays are often used in the study of materials and their surfaces via the techniques of X-ray emission and absorption and photoelectron spectroscopy (ESCA, electron spectroscopy for chemical analysis). In certain studies employing these techniques, the surface cleanliness of the specimen is of prime importance; in these cases the delay caused by oxidation or other contamination of the target surface when the vacuum is broken far exceeds the time normally required to change the target since the target surface must be recleaned, a job which may require tens of hours under hard vacuum condiations.

SUMMARY OF THE INVENTION These delays are obviated by the invention which provides means for translating the anode in two orthogonal directions within the X-ray tube body without requiring the breaking of the vacuum.

THE OBJECT An object of the invention is to enable targets in an X-ray tube to be changed quickly and without breaking the vacuum on either side of the X-ray tube window.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

THE DRAWINGS FIG. 1 is a schematic illustration of an embodiment of the invention;

FIG. 2 is a cross-sectional view taken through the X-ray tube body along the line 2-2 in FIG. 1; and

FIG. 3 is a schematic illustration of an anode as used with the invention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates an embodiment of the invention with a movable anode 12. The apparatus comprises an X-ray tube body 14, a bellows section 16, an insulating section 18, and anode 12, anode longitudinal translating means 20 and anode-transverse-position adjusting means 22. Conventionally, X-ray tube apparatus would not include the bellows section or the anode positionadjusting means.

The X-ray tube body 14 includes means 24 for coupling the inside of the tube body 14 to an evacuating pump, filament feed-throughs 26 through which the filaments 28 enter the tube body 14, an X-ray window 30, e.g., Beryllium foil, and the window holder 32 which may be bolted to the tube body 14.

A bellows 16, comprising a means capable of contracting or expanding in the longitudinal translational direction of the anode 12, is attached to the top edge of the X-ray tube body 14. The bellows 16 may have flanges (34 and 36) at both ends.

A voltage-insulating section 18, which may be of glass, is attached by a flange 38 to the bellows flange 36. The insulating section 18 also has an upper flange 40 to which a anode-holding, or sealing, flange 42 is attached. The anode 12 is affixed to this flange 42 which also seals off the vacuum chamber extending through the tube body 14, the bellows 16 and the insulating section 18.

The anode translating means 20, which may, for example, be a rack-and-pinion device (not shown in detail since these are well known in the mechanical arts) or a screw translation device is affixed to a rigid bar 44 which, in turn, is affixed to the insulating section flange 38. A portion 21 of the rack-and-pinion means is fixed in position relative to the tube body section 14. Thus, operation of the translating means 20 acts to move the insulating section 18 and the attached anode 12 up and down (or longitudinally, the direction of translation) and these translating movement is permitted to occur by the contractibility and expansibility of the bellows 16.

Movement of the anode 12 in a direction transverse to the longitudinal direction is accomplished by the anode transverse-adjustment means 22 which, in this case, comprises a nut and bolt for clamping the rigid bar 44 to a bar extension 45 on the anode translation means 20 plus and enlarged hole 47 in the rigid bar 44 through which the bolt extends. Thus, the rigid bar 44 can be moved transversely before it is bolted down. The transverse flexibility of the bellows l6 permits the anode l2 and insulating section 18 to move transversely when the rigid rod 44 is moved. Actually, the means for adjusting the transverse portion (anode transversing means) could be said to comprise the flexibility of the bellows in the transverse directions, the rigid rod 44 and the enlarged bolt hole in the rod 44. Translation of the anode l2 permits transverse centering of the anode with respect to the window 30 and with respect to the electron-emitting filaments 28 for focusing purposes.

A cross-section of the X-ray tube body 14 taken along the line 22 in FIG. 1 is shown in FIG. 2. The filaments 28 are positioned on both sides of one section of the anode 12 which in FIG. 3, is seen to be a hollow tube, which may be of copper, having a constricted area 46. Water flows through the anode 12 for cooling purposes. The X-ray targets are small areas of film (e.g., a magnesium film target 48 and a aluminium film target 50) only three being indicated although there may be more (the copper anode also constitutes a target). In operation, the anode 12 may be translated to place either target 48 or 50 or the copper tubing under the window 30 where the electrons may bombard the target so that it emits X-rays through the window. The electrons follow a'curved path from the filaments striking the target in front of the window this is described in Demountable High Power Source for Soft X-ray Region, by Deslattes and Simson, Review of Scientific Instruments, Vol. 37, No. 6, June 1966, page 753.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. ln X-ray tube apparatus having a voltage insulating section, an X-ray tube body section which includes an X-ray window, and anode means carrying at least two spaced target areas extending through said tube body past said window in the longitudinal direction relative to said tube body,

anode-positioning means for moving said anode means and its target areas longitudinally with respect to said window, said anode-positioning means comprising bellows means positioned between and affixed to said insulating and tube body sections for providing a longitudinally expandable or contractable section, said anode means extending through said insulating section and said bellows section into said tube body section and being affixed either to said insulating or said bellows section, and anode-translation means having an immovable section and a section which is movable relative to the immovable section, said immovable section being fixed in position relative to said tube body and said movable section being rigidly coupled with said bellows section whereby movement of said movable section expands or contracts said bellows section thereby correspondingly moving said insulating section and said anode means longitudinally past said window thus enabling different target areas to be exposed to the Xray beam as desired. 2. Apparatus as in claim I, further including means rigidly coupled with said section to which said anode means is affixed for transversely positioning said anode means relative to said window.

3. Apparatus as in claim 1, wherein said insulating section includes an upper and a lower flange and said bellows includes an upper flange, said upper bellows flange being affixed to said lower insulatingsection flange, said apparatus further including an anode flange and mounting means, said anode means being affixed to said anode flange which, in turn, is affixed to said upper insulating-section flange and to said anode translation means and including means for moving said mounting means relative to said tube body in the transverse direction. 4. Apparatus as in claim 1, wherein said anode translation means comprises rack-andpinion means. 5. Apparatus as in claim 1, wherein said anode translation means comprises screw translation means. 

1. In X-ray tube apparatus having a voltage insulating section, an X-ray tube body section which includes an X-ray window, and anode means carrying at least two spaced target areas extending through said tube body past said window in the longitudinal direction relative to said tube body, anode-positioning means for moving said anode means and its target areas longitudinally with respect to said window, said anode-positioning means comprising bellows means positioned between and affixed to said insulating and tube body sections for providing a longitudinally expandable or contractable section, said anode means extending through said insulating section and said bellows section into said tube body section and being affixed either to said insulating or said bellows section, and anode-translation means having an immovable section and a section which is movable relative to the immovable section, said immovable section being fixed in position relative to said tube body and said movable section being rigidly coupled with said bellows section whereby movement of said movable section expands or contracts said bellows section thereby correspondingly moving said insulating section and said anode means longitudinally past said window thus enabling different target areas to be exposed to the X-ray beam as desired.
 2. Apparatus as in claim 1, further including means rigidly coupled with said section to which said anode means is affixed for transversely positioning said anode means relative to said window.
 3. Apparatus as in claim 1, wherein said insulating section includes an upper and a lower flange and said bellows includes an upper flange, said upper bellows flange being affixed to said lower insulating-section flange, said apparatus further including an anode flange and mounting means, said anode means being affixed to said anode flange which, in turn, is affixed to said upper insulating-section flange and to said anode translation means and including means for moving said mounting means relative to said tube body in the transverse direction.
 4. Apparatus as in claim 1, wherein said anode translation means comprises rack-and-pinion means.
 5. Apparatus as in claim 1, wherein said anode translation means comprises screw translation means. 